Human behavior is controlled by sensory input through poorly understood mechanisms. Sensory systems that mediate touch, taste, vision, smell, and hearing activate dedicated neural circuits in the brain that process environmental information. These neural circuits control behavior by targeting particular deep brain structures. However, it remains unknown how specific sensory inputs are routed through these brain structures to control behavior. Understanding how neural circuits function to regulate behavior is a basic goal of the neuroscience field, and dysfunction of neural circuits associated with aggression, fear, and other social behaviors is characteristic of numerous human neurological disorders. Here, we study olfactory circuits in mice as a valuable model for understanding how a sensory system can regulate behavior. In mice, pheromones and predator odors are highly controllable stimuli that trigger robust, genetically programmed behavioral responses. In preliminary data, we identified numerous odors that control specific mouse behaviors, and are well poised to study neural circuits involved in mating, aggression, fear, and aversion. We will use a combination of molecular biology, neural circuit analysis, and mouse genetics to study how the mouse olfactory system regulates behavior. We will (1) identify pheromones that control mouse behavior, (2) identify olfactory receptors that detect pheromones, and (3) chart neural circuits activated by pheromones. Generating a collection of pheromones and odors that activate different hard-wired neural circuits and instinctive behaviors will provide a valuable toolbox for understanding the basic function and organization of neural circuits in the brain that underlie social behavior. The ultimate goal of our work is to understand how neural circuits in higher order brain structures organize sensory inputs to control behavior. Understanding general principles of how neural circuits function in the healthy state provides a critical foundation for understanding dysfunction underlying human disease.